Pigment or filler and materials and procedures for making the same

ABSTRACT

A COMPLEX COMPOSITION CONSISTING ESSENTIALLY OF TIO2, SIO2 AND CAO MADE BY PRECIPITATION FROM AN ACID SOLUTION OF TITANYL SULFATE CONTAINING CALCIUM AND SILICATE IONS DISSOLVED THEREIN, BY MIXING SUCH SOLUTION WITH AN ALKALINE SOLUTION UNDER CONDITIONS OF HIGH SHEAR.

March 2, 1971 w, cRAlG 3567,48

PIGMENT'OR FILLER AND MATERIALS AND PROCEDURES FOR MAKING THE SAME Original Filed March 29, 1965 4 Sheets-Sheet. 1

LEGEND i RUTILE T102 A ANATASE Ti 0 29 DEGREES INVENTOR.

WILLIA L. CRAIG March 2, 1971 w. L. CRAIG 3,567,480

PIGMEJNT 0R FILLER AND MATERIALS AND PROCEDURES FOR MAKING THE SAME Original Filed March 29. 1965 4 Sheets-Sheet i SOLUTION C FIG. 4

SOLUTION B SOLUTION A TO STORAGE INVENTOR. WILLIAM L. cams r onmrrs ,March 2, 1971 w, (:RMG A 3,567,480

PIGMENT OR FILLER AND MATERIALS AND PROCEDURES FOR MAKING THE SAME Original Filed March 29, 1965 4 Sheets-Sheet &

PIGMENT CONCETRATION (GMSJLITER) INVENTOR.

wtLuAM A16 ATTORNEYS United States Patent 3,567,480 PIGMENT 0R FILLER AND MATERIALS AND PROCEDURES FOR MAKING THE SAME William L. Craig, Westport, Conn., assignor to R. T. Vanderbilt Company, Inc., New York, N.Y. Original application Mar. 29, 1965, Ser. No. 447,116. Divided and this application June 11, 1969, Ser. No.

Int. Cl. C01g 23/04; C09c 1/36 U.S. Cl. 106-300 12 Claims ABSTRACT OF THE DISCLOSURE A complex composition consisting essentially of TiO SiO and CaO made by precipitation from an acid solution of titanyl sulfate containing calcium and silicate ions dissolved therein, by mixing such solution with an alkaline solution under conditions of high shear.

The application also discloses a complex composition consisting essentially of TiO SiO CaO and BaSO made by precipitation from an acid solution of titanyl sulfate containing calcium and silicate ions dissolved therein, by mixing such solution with an alkaline solution containing barium ion dissolved therein, under conditions of high shear.

The application also discloses the method of producing a TiO pigment of increased rutile content by the sulfuric acid process, which comprises introducing into the high shear zone adjacent a rapidly rotating impeller an aqueous acid solution of titanyl sulfate, introducing into said zone an aqueous alkaline solution of an alkali metal in an amount sufficient substantially at least to neutralize said titanyl sulfate solution and precipitate H TiO withdrawing from said zone efiluent containing said precipitated H TiO removing said H TiO from its mother liquor, and drying and calcining to TiO This is a divisional application of Ser. No. 447,116 filed Mar. 29, 1965.

This invention relates to pigments or fillers containing titanium dioxide, and to procedures and materials used in making such pigments.

Titanium dioxide has been used in the paper industry for many years as an opacifying pigment. One of the problems connected with the use of this pigment in a papermill system is the requirement that the pigment be finely dispersed and uniformly distributed throughout the paper. Titanium dioxide particles are manufactured having mean particle size of about 0.25 micron. This particle size is carefully controlled by the manufacturer to produce the maximum light reflectance or opacity. When the pigment is used in a papermill system it is difficult to maintain the proper dispersion because the small particles of TiO must be flocculated in order to retain them in the fiber matrix. Such flocculation or piling reduces the desired optical efficiency of the titanium dioxide pigment.

The dispersion problem has been studied by pigment chemists for many years in an attempt to obtain a better pigment for the paper industry. Various pigment extensions were made by physically blending TiO with other inorganic compounds such as barium sulfate, calcium sulfate, calcium silicate, aluminum silicate and hydrated silicates. Such extended pigments were used throughout the paper industry for many years. However, the purchase of "ice such materials is not favored because in some instances it has been found more economical merely to blend the individual components of the mixture at the papermill.

Similarly, in the paint, rubber and other fields, TiO has been blended with extenders such as CaSO BaSO aluminum silicates to reduce the cost of the material. Such extenders serve to keep the TiO particles separated in the matrix and reduce piling which, in turn, produces a higher degree of optical efficiency from the TiO;;. Although the physical extension of the TiO;, particles does in some measure increase the opacity of the material such as the finished sheet of paper, rubber, paint film, etc. the efficiency of the TiO particles is still far below their maximum capabilities.

In accordance with the present invention there is produoed a complex composition consisting essentially of TiO SiO and CaO made by precipitation from an acid solution of titanyl sulfate containing calcium ions and silicate ions dissolved therein, by mixing such solution with an alkaline solution under conditions of high shear. According to a particular embodiment of the invention, there is produced a complex composition consisting essentially of TiO SiO C210 and barium sulfate made by precipitation from an acid solution of titanyl sulfate containing calcium ions and silicate ions dissolved therein, by mixing such solution with an alkaline solution containing barium ions dissolved therein under conditions of high shear. A novel aspect of the invention is the aqueous acid solution of titanyl sulfate containing calcium and silicate ions dissolved therein, which upon being neutralized with an alkali precipitates the complex TiO SiO and CaO. As the term is used in the specification and claims, TiO includes both the anhydrous form and TiO in the form of the hydrate H TiO According to the method of the invention the complexes are preferably produced by continuously introducing into a high shear zone adjacent a rapidly rotating impeller, an aqueous acid solution of titanyl sulfate containing the calcium and silicate ions dissolved therein, and simultaneously continuously introducing into said zone an aqueous alkaline solution of an alkali metal (suitably containing the barium ion dissolved therein if desired) in an amount sufficient substantially to neutralize said titanyl sulfate solution, and preferably raise the pH to a value between about 8 and 10, thereby to precipitate the desired complex. The effluent containing said precipitated complex is continuously withdrawn from the high shear zone.

The slurry containing the complex dispersed in the mother liquor is then filtered or centrifuged to recover the complex, which is thereafter dried, calcined and ground to produce the pigment having the desired particle size and suitably dispersed particles. The precipitated complex pigment will have an average particle size not greater than 0.5 micron, preferably, under optimum conditions, not greater than about 0.25 micron.

In the case of pure TiO there is a rather critical particle size range needed to obtain maximum opacity, i.e., about 0.20.25 micron. With my extended pigment, however, made by the procedures described herein, and containing at least about 25% of extending material, the permissible particle size range is about 0.15 to 0.5 micron for maximum opacity. The preferred amount of extender is about 60-70%, that is, about 30-40% TiO It has been found that upon calcining the Ti0 or the TiO complex obtained according to the invention, a TiO pigment is obtained (Without seeding) which has a substantially higher Rutile content as compared with TiO pigments obtained by ordinary sulfuric acid procedures (without seeding). Therefore, a particular aspect of the invention resides in the method of producing a Ti pig ment having increased Rutile content by the sulfuric acid process, even in the absence of CaSiO and BaSO by carrying out the process described under conditions of high shear, preferably by continuously introducing into a high shear zone adjacent a rapidly rotating impeller, an aqueous acid solution of titanyl sulfate, simultaneously continuously introducing into said zone an aqueous alkaline solution of an alkali metal in an amount sufficient substantially to neutralize said titanyl sulfate solution and preferably raise the pH to a value in the range of about 8-10, thereby to precipitate H TiO continuously Withdrawing from the zone the effluent containing the precipitated H TiO which is then removed from its mother liquor, dried and calcined to produce TiO The calcining is carried out under known conditions.

FIG. 1 is an X-ray diffraction diagram of a TiO pigment made according to the invention;

FIG. 2 is another X-ray diffraction diagram of a TiO pigment made according to the invention;

FIG. 3 is still another X-ray diffraction diagram of a TiO pigment made according to the invention;

FIG. 4 is a diagramamtic section of a portion of a centrifugal pump useful in carrying out the process of the invention;

FIG. 5 is an enlarged drawing of a portion of the pump shown in FIG. 4;

FIG. 6 is a diagramamtic section of the pump shown in FIG. 4 taken along the axis of the impeller; and

FIG. 7 is a diagram showing light absorption of water suspensions made according to the invention.

It is not known exactly why the conditions set forth above produce the unexpected results that have been found. It is thought, however, that as the alkaline solution, suitably containing the barium ion, combines with the strongly acid titanyl sulfate solution, the following reactions may occur instantaneously and simultaneously:

(1) The titanyl sulfate instantly hydrolyzes to titanic acid (H TiO (2) The barium salt (if present) reacts with the available sulfate ions and forms an insoluble barium sulfate and the calcium ion combines with SiO to form the hydrated calcium silicate. It is noted that under these conditions calcium sulfate cannot be formed since it is soluble.

(3) The control of the extent of shear at the point of mixing and precipitation is believed to be important. The two major controlling factors for this formation are temperature and agitation. By maintaining the rate of shear at its maximum value and the temperature at its optimum value, the ultimate fineness of the discrete particles as formed is assured.

(4) The fact that all the chemical constituents involved in the reaction are soluble and ionized permits simultancous double decomposition of the salts to form the insoluble complex structure.

The rate of TiO to the other components of the complex may be varied over a Wide range. In fact, substantially pure TiO may be made utilizing the present invention. The content of barium sulfate and calcium silicate will depend generally upon the use to be made of the pigment. For reasons of economy it will be desired to include as 'much calcium silicate and barium sulfate as can be tolerated since they are relatively less expensive materials. A suitable range of TiO; content for the extended pigment is about 5 to 95%, preferably about 5 to 40% TiO based on the totai weight of the complex, the remainder representing the content of CaO, Si0 and BaSO; (if present).

The ratio of the barium sulfate to the calcium silicate may also be varied, suitably within the range from about 95:5 to 5:95 by weight. Since the B2150, is a dense material and the hydrated calcium silicate is a relatively less dense and bulky material, it is preferred, particularly from the standpoint of the fired product, to balance these characteristics of the two materials. The preferred amounts are about equal on a weight basis but acceptable qualities may be obtained in the range of about 30:70 to 70:30 of the two materials.

The techniques useful in controlling the precipitation of the pigment and the characteristics of the precipitated pigment include temperature, pH, water dilution and degree of shear. The temperature within the zone of high shear where precipitation occurs, is preferably elevated, thereby to make the reaction go more rapidly. Temperatures within the range of about IOU-212 F. are suitable, but they are preferably in excess of F.

The temperature of a titanyl sulfate solution before it reaches the zones of high shear, however, is governed by other factors. Excessively high temperatures will cause the titanyl sulfate to hydrolyze prematurely and the titanium to precipitate. Accordingly, the temperature of the titanyl sulfate solution is maintained below the thermal hydrolysis temperature, which is about 170 F.

The titanyl sulfate solution will, of course, be strongly acid. The pH will generally be about 1.0 or less, and low enough to keep the titanium and the calcium and the silicate to be added, in solution. The calcium chloride solution and the sodium silicate solution are added to the strongly acid titanyl sulfate solution and the components are mixed together. Although the solution is concentrated with respect to sulfuric acid, the TiO content is only about 20%, that is about 0.3 gram per cubic centimeter. The solution is then diluted with water, preferably hot water, to reduce the TiO concentration to below about 10%, preferably about 2% or lower. The diluted hot solution is added as soon thereafter as practical to the high shear zone.

Although the reaction may be carried out using the concentrated titanyl sulfate solution, the dilution affords easier control of the reaction to produce the desired product.

The type of sodium silicate employed is not critical. However, it is preferred to use a sodium silicate that has a high SiO content, inasmuch as it is the SiO which will appear in the fiinal product. A suitable material is Na O-3 to 4 SiO Other alkali metal silicates, such as potassium silicate may be used. The use of calcium chloride is not critical and, in fact, other soluble and compatible calcium salts may be used.

The ratio of CaO to SiO in the final complex will depend, of course, upon the ratio of calcium to silicate added to the titanyl sulfate solution. This is a factor which is subject to wide variation depending upon the qualities desired in the final product. For example, the more dense CaSiO in which the ratio of CaO to SiO is 1:1 may be formed. This may provide advantages, particularly where little or no BaSO is present. It is preferred, however, to have a relatively high ratio of SiO to CaO, that is above about 3:1, which is a less dense and more bulky material.

Although sodium hydroxide is preferred for reasons of economy, other strong alkalies, particularly alkali metal alkalies such as potassium hydroxide may be used. The temperature of the caustic solution before it reaches the mixing zone is not critical unless barium salt is present. In the latter event, the time and the temperature of the alkaline solution containing the barium salt are controlled between the point of mixing the barium salt with the alkali and the high shear precipitating zone to prevent precipitation of barium hydroxide. Preferably the barium salt is added just before the zone of high shear, and the temperature of the alkaline solution is maintained at about ISO-200 F. Barium chloride is preferred but other soluble and compatible barium salts may be used.

The following examples are presented to illustrate the invention, the parts expressed being on a weight basis unless otherwise indicated.

EXAMPLE 1 One source used for the titanium was a titanium bearing iron slag known as Sorel slag. This slag contains about 75% TiO and approximately 8% iron (FeO). The following components and materials were used in preparing the ore:

Components: Parts Ilmenite (Sorel) ore 75 Concentrated H 80 (96%) 225 Dextrin 0.45 0.1 N H 80 250 As O 0.13 FeS 0.18

The ore was ground in a ball mill to fineness that would pass through a 200 mesh screen. The correct amount of ground ore was then placed in a three-necked fiask and the concentrated sulfric acid was added to the flask. A mercury seal agitator system was inserted in the center neck of the flask, a water condenser in another neck of the flask, and a 400 C. thermometer in the remaining neck of the flask. The sulfuric acid Ilmenite slurry was heated under constant agitation to 125 C. At this point the dextrin was added to prepare for the exothermic reaction. The heating was continued until a temperature of 220 C. was reached at which point the slurry formed into a solid cake. The cake was allowed to cool to 60 C. and the correct amount of 0.1 N H 80 was added to the flask and the cake was dissolved into solution. The correct amount of As O was then added and allowed to mix for 15 minutes. Then the FeS was added and mixed well for 30 minutes. The arensic and the iron treatments were used to aid in the clarification of the liquid. About 2 liters of distilled water were added to the mixture to assist in filtering, and the liquid was filtered in a Buchner system with an acid filter paper to remove undigested sludge.

At this point the titanium and iron were in complete solution and the liquor was ready for the next processing step. The iron in the liquor (as ferrous sulfate) was completely soluble in extreme dilutions, whereas the titanyl sulfate hydrolyzes on dilution to H TiO which is an insoluble precipitate. Therefore the iron was removed by the following procedure.

One volume of the liquor was slowly added toten volumes of boiling water, the titanyl sulfate instantly hydrolyzed to titanic acid (H TiO The mixture was filtered and thoroughly washed in a Buchner system. The filtrate contained the ferrous sulfate and was discarded. An amount of sulfuric acid equal to the sulfuric acid content of the original liquor was slowly added to the wet filtered cake of H TiO in a 4 liter beaker, a little bit at a time under continuous mixing. The heat of the solution is usually sufficient to raise the temperature to approximately 125 C. at which point the titanic acid reverts to the titanyl sulfate; if not, heat is added slowly while mixing continuously. At this point the liquor was purified and contained only titanyl sulfate. This liquor was referred to as black liquor. It contained the equivalent of about 0.144 gram of TiO per milliliter and at this point was ready to receive the other inorganic chemicals in preparation for the final precipitation of the complex. Other procedures known in the prior art may be used for preparing the purified (iron free) black liquor.

1200 milliliters of water at 140 'F. were added to 42 ml. of the black liquor; 30 ml. of a calcium chloride solution CaCl by volume) were then added; 40 ml. of a sodium silicate solution (18.5% Na O3.25 SiO by volume) were added to complete the black liquor preparation. This solution was strongly acidic and contained titanium, silicon dioxide and calcium, all in solution in the sulfuric acid. The black liquor was now ready to be precipitated to produce the desired complex pigment.

To 1600 ml. of water at 200 F. were added 53.6 ml. of a barium chloride solution (10% BaCl by volume). 215 ml. of 5 N NaOH solution was prepared. The diluted black liquor solution (1312 ml.) was placed in a high shear reactor, that is a Waring type commercial blender Model CB-3, 1 gallon capacity, 14,500 rpm, /2 HP. The black liquor in the reactor was placed under high shear and the 5 N caustic solution was quickly added to the barium chloride solution and this mixture was added as fast as possible to the reactor. This technique produced an instantaneous reaction with all of the available compounds and the insoluble pigment precipitate was thereby formed. The precipitated pigment was thoroughly washed and filtered in a Buchner system and dried in a low temperature oven (175 F.)

The pigment was refined as follows. After the reacted pigment was thoroughly washed and dried, it was ground in a hammermill to reduce the agglomerates to an optimum particle size. The grinding was controlled to produce a pigment having less than 0.1% grit on a 325 mesh screen. Samples of the pigment were calcined in a fur nace to determine the optical properties of the particle after loss of the water of crystallization. Firing is suitably carried out in a mufile furnace from 400 to 2200 F. preferably at about 1800 P. All of the combined water (15% ignition loss) was removed at temperatures below 600 F. The calcined samples were again ground in the hammermill to the above-mentioned specification. The following physical and chemical properties were determined in the product.

The properties indicated in the following table are those of pigment before the refinement procedure.

UNCALCINED PIGMENT G. E. Brightness-+ Loss on Ignition--approximately 15% Assay-approximately 33% TiO (as H TiO 33% CaO.4SiO .xH O (where x varies between 3 and 4), 33% BaSO Handsheetsof paper were made and tested in accordance with the following procedure.

A sufficient amount of 3% consistency bleached sulphite stock (about 350 C.S.F. TAPPI Specification T227m-58) to contain 20 gm. of bone dry fiber was weighed out and put under agitation. To this concentrated stock there was added 4 cc. of a 5% resin size solution (1% on the weight of the fiber), a sufllcient amount of the ground pigment slurry to contain 1.2 gm. of dry pigment (6% on the weight of the fiber), and 8 cc. of a 5% iron-free alum solution (2% on the weight of the fiber) in that order, allowing 15 minutes of mixing after each addition. This concentrated stock was diluted to a total volume of 7,600 cc. in a large pail with filtered tap water and the pH was adjusted to 4.0-4.5 with 1% sulfuric acid. 590 cc. aliquots of this stock were put under mild agitation and 7.5 cc. (1 pound/ ton based on 1.5 gm. of fiber) of a 0.01% Vanzak RA (a high molecular weight synthetic polymer cationic retention aid) solution was added and allowed to mix slowly for 2 minutes. The stock was then added to the mold, the pH adjusted to 4.045 with a 1% sulfuric acid solution, and the handsheets prepared following TAPPI conditions. The sheets were pressed, dried and conditioned overnight beforetesting. The TAPPI brightness of the sheets and the opacity of the sheets were measured and found to be acceptable.

EXAMPLE 2 The black liquor was prepared according to the procedure described in Example 1 and contained 0.106 gm. of TiO per ml.; 1200 ml. of water at F. were added to ml. of the black liquor; 5 ml. of a calcium chloride solution (10% CaCl by volume) were then added; 7 ml. of a sodium silicate solution (18.5% Na 0.3.25 Si0 by volume) were added to complete the black liquor preparation. This solution was strongly acidic and contained the titanium, silicon dioxide and calcium, all in solution in the sulfuric acid. The following procedure was used to initiate the formation of the precipitated pigment.

(1) 9 ml. of a barium chloride solution (10% BaCl by volume) were added to 250 m1. of water at 130 F.

(2) 1100 ml. of N NaOH solution were added to 500 ml. of distilled water and the solution was heated at 200 F.

(3) The treated black liquor solution was placed in a high shear reactor of the Waring type described in Example 1.

(4) The black liquor in the reactor was placed under high shear, that is the agitator of the blender was operated at maximum speed and the 5 N caustic solution along with the barium chloride solution were added simultaneously to the reactor.

The foregoing procedures produced an instantaneous reaction with all of the available compounds and the insoluble pigment particles were formed at the prevailing pH which was about 10.0. The precipitated pigment was thoroughly washed and filtered on a Buchner system and dried at a low temperature hot air circulated oven (175 F.). The pigment was ground in a mortar and pestle to a relatively fine particle size. Samples were then calcined in a furnace to determine the optical properties of the particles after the loss of the water of crystallization. The calcined samples were then wet-ground in a ball mill for 72 hours. The grit was controlled to pro duce a pigment having less than 0.1% grit on a 325 mesh screen. Handsheets were prepared according to the procedure described in Example 1. The results are presented in the following Table I (under the heading Test No. 2) together with similar data obtained by using other TiO pigments.

6 6 6 1 lb/ton based on 1. 5

Vanzak RA "I:

gm. of fiber weight pH to pail 4. 1 4.1 pH to mold 4.2 4.2 4.2 Handsheet tests:

Basis weight (25X38-500) 43. 6 52. 2 48. 4 TAPPI brightness 75. 4 79. 1 75. 9 TAPPI opacity 86. 5 88.1 87. 7 Percent TiOr in sheet 4. 43 3. 65 4. 3 Determination of the pigment efiiciency value:

SX value 2. 83 3. 27 3. 01 Corrected SX value (50 lb. basis weight 3. 1O 3. 14 312 Corre ed opacity (50 lb. basis weight) 88. 6 87. 2 88. 4 Pigment efliciency value 700 860 720 Test No. 1 is a pure TiO prepared from the original black liquor by mixing the black liquor with boiling water with moderate agitation. Test No. 3 is a product prepared in the same way as Test No. 2 (high shear mixing) with the exception that no calcium chloride, sodium silicate or barium chloride were added.

The data appearing at the lower part of Table I under the heading Determination of the Pigment Efiiciency Value are calculated values to correct for diiferences in the basis weight of the three samples. The conversions were made by standard procedures as follows:

By the standard procedure described in TAPPI Standard T425m Opacity of Paper, using a Bausch & Lomb Opacimeter, the reflectance over black R and the TAPPI opacity, C were measured on the paper. Using the Kubelka and Munk chart, the intersect of these values was located and the scattering coefiicient SX was obtained. Also using standard procedure, the basis weight was corrected to exactly 50 pounds and the new SX value was obtained. The percent titanium dioxide was determined on the basis of the ash content of the papers. The Pigment Efiiciency Value was then calculated according to the following formula:

Pigment CffiClGIlOY value=m EXAMPLE 3 Following the procedure described in Example 1 a composite pigment was made containing 38% TiO 31% BaSO and 31% CaO.4SiO

The product of Example 3 and two of the products from Example 2, that is Tests Nos. 2 and 3, were examined by X-ray diffraction using a standard Norelco high angle automatic diifractometer, utilizing nickel filtered copper radiation. The charts obtained are presented herewith as FIGS. 1, 2 and 3. The instrument operated at 40,000 volts, and 20 milliamps plate or tube current. The divergent slit which meters the X-ray beam from the tube has 4 of arc. The receiving slit between the source and the sample has an aperture of 0.006 inch. These provide a nearly point source of X-rays for impingement upon the specimen. The scatter slit had an opening of 4, this being the slit which allows acceptance of the reflected and/or diffracted X-rays leaving the specimen. Scale F was used (1/8/1) with the time con stant of one. The receiving head assembly is rotated relative to the incident beam at a rate of 2 per minute. The strip chart is pulled past the pen at such a rate that 4 of receiver head movement occurs during each inch of chart movement (abscissa of the graph). The diagrams of FIGS. 1-3 were reduced to about one-half the original size.

Numerical values assigned to each peak represent the distance between parallel planes within the crystal in angstrom units. They are arrived at from Braggs Law using the equation 7\ 2 sin 0 where:

7\=wave length of the rays; D=distance between the atomic planes; and 0=ang1e of incidence of the rays.

The wave length of copper Koc is 1.54 A. and in this case the equation reduces to 1.54 2 sin 0 There are a number of unidentified lines which do not correspond to any calcium-silicon-oxygen compound. In FIG. 3 (the product of Example 3) the diagram also indicates large amounts of TiO as Rutile. BaSOi, is the other major component of this material. Unidentified 10 20RVL-5 having a capacity of 150 g.p.m. at a 52ft. head, an impeller diameter of 11 inches, and a power input of HP. at 1150 rpm.

In carrying out the procedure of the invention, a solution A, which is the titanyl sulfate, and is at a temperalines are also present. These data indicate that in the 5 ture of 140 F. is introduced at the inlet 11. Solution B case of FIG. 2 (80% TiO and FIG. 3 (38% TiO introduced through the connection 21 is the alkaline soluthe compounds are true complexes of CaO, SiO and tion at a temperature of 200 F. Following the procedure BaSO present together with the TiO described in Example 1 the following additional Examples EXAMPLES fl, 5, 6, 7, 8 and 9 were carried out by simultaneously introducing an acid tltanyl sulfate solution at 11 and a Referl'lflg to 4 9 6 Whleh llhletrate the design mixture of sodium hydroxide solution and barium chloand use Of q p f Sultahle for {haklhg the plex ride solution through the Y connection 22 and into the compositions of T10 ona commercial scale, the followpipe o tio 20, I Example 9 o Bacl wa added. A mg pfeeedllres e earned ol'lt 111 the lfp ShOWhproduct consisting of a slurry of the precipitated pigment A portion of a casing of a suitable centrifugal pump 10 in the aqueous mother liquor was removed from the pump havlhg an Inlet a dlseharge and an Impeller at 12 and treated to separate the precipitated pigment, rotatlng about an 3X15 16 1S ShQWH 111 4. In 3 after which it was dried and calcined as described above. there 15 Shown 011 an ehlarged Seale an lhlet P p 20 The products of Examples 4 to 9 contained the following taehed t0 the P p easlhg 10 at Y adlaeeht 10 20 respective amounts of Ti0 (the remainder being CaO, the connection 21 there is a Y 22 having two branches SiO and BaSO 100%, 95%, 80%, 5%, 40% and 40%. and 26. The pump may itably be a Closed impe The reaction conditions and the properties of the product pump such as Ingersoll-Rand Motor Pump Model are set forth in the following table.

TABLE II Final Titanium dioxide, complex mixture Example 4 Example 5 Example 6 100% TiOz 95% T102 80% Tio2 (No complex) 5% added 20% added Amounts of chemicals used in preparation (according to system given to the light) For 100 For 150 For 100 1b. For 100 For 150 lb. TlO2 produc- TiOz 1b.TiOz produccalcined tion calcined calcined tion yield g.p.m. yield yield g.p.m.

Titanyl sulfate (0.1060 gins. TiOz/ITIU, gallons 113 9.0 113 113 9.0 Dilution water for titanyl sulfate, gallonsubunfiu 3 8q 0 (lb 987 81 987 181 W a ki s. 17.8 .5 Sdmm {gal ?Jf1g3i75(% solitgon 2. 4 1 11. 5 8. ry a poun s .57 .7 Calclum chlmde $31.10; i i jgioluti n) g. l' a v S Banumimmlde g g g ii iiiio t 1 g g 1 W a poun s 1, Sodmm dwxde Gal. of 5 normal solution 720 00 720 720 60 T t 1y 1 1 HQTIOQ B g 0 n 123 1 1 2 0'3 is 011 S 3. 2 .4.

p f "{CaO-fSiO -3H O 3. i 14. 9 1. 22 c l dY' ld( d "ifs 6 l 100 2 g 12 i? C11 16 01111 S L a a a w p Cmnplex --{cao.4 sio2 2.6 12.5 1.02

Final titanium dioxide, complex mixture Example 7 Example 8 Example 9 5% TiOz TiOz 40% 'liOz 95% added added 60% added (no barium) Amounts of chemicals used in preparation (according to system given to the right) For 100 lb. For 100 For 150 For 100 For 150 TiOz lb. T102 produc- 1b. T102 produccalcined calcined tion calcined tion yield yield g.p.m. yield g.p.in

Titanyl sulfate (0.1060 gins. TiO /mlJ, gallons 113 113 9.0 Dilution water for titanyl sulfate, gallons i l f 1 88% ry a2 2 1 Sd1um slhcate- "{Gal. of18i75(% soliaitiom 27:1 g

- Dry CaC 2 poun s 5 Calcmm Ohlmlde Gal of solution) 4% 2.8 Dry Ba (pounds 8 6 5.5 Baum chlmde g 0f109 S(01ul2l0[I11.) 1 3 1 5. 3

. ry NaOH poun s Sodium hydloxlde' "{Gal. of 5 normal solution 720 720 50 {I'I2Tl03- $1323 123 Total ield ounds) BaSO 50 y (p Complex {CaO-4SiO2-3HZO 1,132 89.6 7.35 TlOz $1308 Calc'ned icld ounds 5 75 1 y (p {Complex 950 75 6.17

EXAMPLE 10 Aqueous suspensions were prepared from a number of pigments and the percentage of transmission of light at 500 microns was measured for each such suspensions to determine the opacity of each of the particular pigments. Pigment A was an Anatase pigment of a commercial grade known as Rayox RG. It had an average particle size of about 0.25 micron. Pigment B was a type of clay sold commercially under the name Spray-Satin. It is a No. 1 fraction coating grade of Kaolinite (the finest grade) having an average particle size of about 0.5 micron. Pigment C was titanic acid (H TiO obtained by the sulfuric acid process and calcined but without being seeded with Rutile Ti It was prepared in Example 2, Test 3 above. Pigment D was the extended pigment containing 38% TiO prepared in Example 3 above. Pigment E was the 80% TiO pigment prepared in Example 2, Test 2. "Each of the pigments A through B after being Wetround in a ball mill was made up in the following cou eentrations: 7

Gan/liter These were then measured on the Bausch & Lomb Spectronic colorimeter at 500 microns wave length. Standard Bausch & Lomb selected test tubes were used to contain thedispersions during all measurements. The results of such measurements are plotted on FIG. 7 which is a semi-log graph as a function of the concentration of the particular dispersion.

It'has been established that relatively dilute suspensions of titanium dioxide pigments follow the Beer-Lambert Law, i.e., the relationship between the logarithm of the light transmitted through the dispersion and the concentration of the dispersion is a straight line over the measurable limits of the instrument. Therefore, by plotting the logarithm of the percent transmittance versus the concentration, a straight line is obtained. All the lines extrapolated to one common point (100% transmission at zero percent pigment dispersion). The curves with the greater slope have the greater opacity per unit of pigment (since they allow less transmission). The relative opacitying powers of the pigments, therefore, can be determined by measuring the relative slopes of the curves as shown in FIG. 7. It will be observed from FTG. 7 that the product of Examples Z and 3, that is those containing 80% TiO and 38% TiO respectively, had a significantly better opacity than pure Anatase and clay. Sample C, which was 100% Ti0 prepared by the procedure of Example 2, also showed a significantly higher opacity than the pure Anatase.

Although the uses of the compositions and methods of the invention have [been illustrated in connection with the manufacture of paper, they are also useful in the manufacture of elastomeric products such as rubber as a pigment and/or filler, in the manufacture of paint as a pigment and/ or extender, and in still other products.

I claim: 7 i

1. A complex composition consisting essentially of TiQ SiO CaO and BaSO made by precipitation from an acid solution of titanyl sulfate containing'calcuim and silicate ions dissolved therein, by mixing such solution with an alkaline solution containing barium ion dissolved therein, under conditions of high shear, thejratio of BaSO to the sum of SiO and CaO being in theirange of 95:5 to 5:95,

the amount of ,,Ti0 being in the range of about 5% to 40% and the ratio of SiO to CaO being at least about 3: 1.

2. A composition as describedin claim 1 in which the ratio of BaSO to the sum of the CaO and SiO is in the range :70 to 70:30. 7

3. A composition as described in claim 1 which the TiO; content is in the range of about 30% to 40%.

4. The method of producing a complex composition consisting essentially of TiO SiO CaO and BaSO which 1 comprises continuously introducing into the high shear zone adjacent a rapidly rotating impeller an aqueous acid solution of titanyl sulfate containing calcium and silicate ions dissolved therein, simultaneously introducing into said zone an aqueous alkaline solution of an alkali metal cantaining barium ion dissolved therein amount sufiicient at least substantially to neutralize said titanyl sulfate solution and precipitate said complex, and withdrawing from said zone efiluent containing said precipitated complex, the amounts. and proportions of titanyl sulfate, silicate and calcium ions and barium ion being such that in the complex composition the ratio of BaSO to the sum of SiO;,, and Cat) is in the range 95 :5 to 5 :95, the amount of: TiO is in the range of about 5% to about 40% and the ratio of SiO to CaO is at least about 3: 1.

5. The method of claim 4 in which said titanyl sulfate solution and said alkaline solution are mixed in the high shear. zone adjacent the impeller of a centrifugal pump by continuously introducing said solutions to said zone.

6. The method of claim 4 in which the titanyl sulfate 30 solution is kept below its hydrolysis temperature until it reaches said high shear zone.

7. The method of claim 6 in which the pH of the resulting mixed solutions is about 8 l 0.

8. The method of claim 4 in which the temperature of the mixed solutions is about loo-212 F.

9. The method of claim 8 in which the temperature of v the mixed solutions is at least about 170 F. t

10. The method of clairr 4 in which the alkaline solution is prepared by adding BaCl to aqueous NaOH solution, the resulting mixture being at a temperature of about 1802'00 F., and such mixture is immediately introduced into said high shear zone. 11. A complex composition consisting essentially of TiO SiO CaO and 'BaSO the rat-i0 of 'BaSO to the sum of SiO and CaO being in the range of 95:5 to 5:95, the amount of TiO being in the' range of about 5% to 40% and the ratio of SiO to CaO being at least about 3:1, made by precipitation from an acid solution of titanyl sulfate containing calcium and silicate ions dissolved therein, by mixing such solution with. an alkaline solution containing barium ion dissolved therein, under conditions of high shear, filtering and calcining the precipitate at a temperature of about 1600 to -1800 F., the TiO in said composition being predominantly in the form of rutile.

12. A composition as described in claim 11 in which the composition has been further ground and classified.

References Cited UNITED STATES PATENTS 5/1933 Washburn et a1 106-300 5/1956 Grave l06300 US. 01. X.R. 23-202; 106-299, 306;;162181; 260'--746 3,567,480 March 2, 1971 Patent No. Dated WILLIAM L. CRAIG Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

TABLE II, line 15, "0.57" should be 0.97

TABLE II, line 22, "2.5" should be 2.6

TABLE II, line 25, "BaSO should be BaSO TABLE II, line 44, "66.5" should be 66.6

TABLE II, line 50, "89.6" should be 89.4

Column 3, lines 27, 32, "diagramamtic" should be diagrammatic Column 3, line 59, "rate" should be ratio Column 5, line 34, "arensic" should be arsenic Column 7, line 43, "SiO should be SiO Column 11, line 64, "calcuim" should be calciur UNITED STATES PATENT OFFICE 5 9 CERTIFICATE OF CORRECTION Patent No. ,480 Dated Marbh 2, 1971 Inventor) WILLIAM L. CRAIG PAGE 2 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

TABLE II, line 40, "17.0" should be 17.6

Column 6, lines 30-32, delete sentence reading:

"The following physical and chemical properties were deterrnined in the product", and substitute therefor: The properties indicated in the following table are those of the uncalcined pigment before the refinement procedure.

Column 6, delete lines 33, 34 and 35.

Signed and sealed this 30th day of November 1971.

(SEAL) Atteflt EDWARD M.FLETGHER,J'R. ROBERT GOI'TSCHALK. Attesting Officer Acting Commissioner of Patents 

